Safety device for electrical appliances



May 19, 1936. P. M ILVENEY 2,041,362

SAFETY DEVICE FOR ELECTRICAL APPLIANCES Filed July 19, 1954 I UNITED STATES PATENT OFFICE SAFETY DEVICE FOR ELECTRICAL APPLIANCES Patrick McIlveney, Devonport, Auckland, New Zealand Application July 19, 1934, Serial No. 736,083

4 Claims.

The invention relates to safety devices used with electrical appliances, to which current is supplied for heating purposes, and has for its object the provision of an improved form of safety device of that class, wherein parts of the safety device are held together by a fusible solder, so that upon the device becoming overheated, the solder fuses and permits the parts to separate, and be responsible for the cutting off of electric current to the appliance.

According to the invention there is provided in the electric circuit of the appliance a spring contact which is maintained closed by means of a detachable plate comprising portions united by a fusible solder, one of said portions being secured to the casing containing the switch, and the other of said portions acting on a spring contact supporting member to normally retain the spring switch in its closed position.

20 In order however, that the invention may be better understood it will be more particularly described with the aid of the accompanying drawing, Where, as an example, the improved safety device is illustrated, as applied to a plug used with 25 a domestic electric iron.

In the drawing:

Figure 1 is a plan view of the plug,

Figure 2 an inside view of the portion thereof, containing the safety device,

30 lgigure 3 a longitudinal sectional view thereof,

Figure 4, a sectional elevation enlarged of the safety device itself.

As applied to a plug, I with a flexible lead 2 and guard 3 attached and adapted for use with an electric iron, or other appliance, the wires I of said lead 2 are connected to separate terminals 5, one of which is permanently electrically connected with one of the usual spring jaw contacts 40 6, by a bar I, the other of said terminals 5 being electrically connected to a spring contact 8 which normally moves away from a stationary contact 9 electrically connected with the other spring jaw contact 6.

45 In order to keep the spring contact 8 against the contact 9, so that a closed circuit through the appliance to which the plug I is fitted, can be obtained, in the usual manner upon closing an external switch, a headed pin III of material which 50 is a non-conductor of electricity is made to extend through a hole in the side of the plug I in which the contacts 8 and 9 are fitted, and a plate II is secured by a screw I6 to the plug I, so as to push the pin III inwards against the contact 8 and the 55 latter against the contact 9.

The plate II contains a hole I2 with a slight rim I la encircling same and around which is secured to said plate by fusible solder I3, a flanged cup I4 (shown inverted in the drawing), containing a hole I5.

The plug I is recessed to accommodate the cup I4, the hole I5 in which receives the body of the screw I6, so that the latter holds the plate II in position with the pin I0 pushed inwards against the action of the spring 8, to maintain an electrical connection between the latter and the contact 9.

Upon the plug I becoming heated beyond a predetermined degree, the solder I3 melts, whereupon the plate II fails to withstand the opening action of the spring 8 transmitted through the pin Ill, and permits itself to be pushed away from the cup I4, so that the spring 8 moves from the contact 9 and opens the electric circuit through the appliance.

To put the plug into normal working order again, a new plate II with a cup I5 attached by a solder as described, is procured and secured against and in the plug I as shown by the screw I6 to cause the pin II] to reclose the contacts 8 and 9.

By providing the pin III with a head, it is prevented from falling out of the plug I, following removal of the plate I I.

Ribs or guards I8 on the side of the plug I to which the plate I I is fitted ensure that the latter can be secured to the plug, only one Way to push inwards the pin I0 and also to ensure that said plate II will clear the. housing on the appliance, in which the plug I is inserted in use, to enable the plate to function upon the solder melting.

Insulating partitions I9, separate the jaw contacts 6 from the contacts 8 and 9.

The casing I is in the usual two portions adapted to be secured together by the usual screw bolts II and the screw I6.

What I do claim and desire to obtain by Letters Patent of the United States of America is:

1. A safety device for use with electrical appliances, comprising a casing, a spring contact, a recessed portion seated in and detachably se- 5 cured to said casing, a fiat plate portion, fusible solder securing said flat plate portion to the recessed portion, and fitting flat against the exterior of said casing; and a pin extending through said casing and being retained in position by said fiat plate portion to press against and to retain the spring contact in its closed position.

2. A safety device according to claim 1, wherein the recessed portion is cup-shaped having a hole in the cup part thereof, and means extending through said hole and means securing the recessed portion to the casing.

3. A safety device according to claim 1, wherein the recessed plate portion is cup-shaped and has a hole therein, and wherein the flat plate portion contains a hole adapted to register with the cupshaped portion when the recessed portion and the plate portion are soldered together, and securing means extending through the said casing, for

10 fastening the recessed portion and the plate portion to the casing.

4. A safety device according to claim 1, wherein the recessed portion, which is adapted to be secured to the casing, is formed separate from the plate portion, and contains a cup with a hole therein, and surrounded by a. flange, said other portion containing a. hole surrounded by a rim around which latter said flange is adapted to be secured by the fusible solder. 

